July 2i, 1885.] 



KNOW^LEDGE 



fault is actually indicated on the surface by the number 

 of brick-pits which work the "fault-stuil," as the 

 rubbed-up clayey matter between the two sets of rocks 

 may be called ; moreover, all the diorite bands end 

 abruptly against it. Proceeding eastward, we enter a 

 cutting in which the Cambrian shales are capitally 

 exposed. They consist of grey, black, and purple 

 to red shales — the latter lying at the base. They 

 dip to the south-west at from 55° to 65°, and the 

 height of the cutting is from 20 ft. to 30 ft. 

 Nodules of manganese occur in the red shales, 

 and they were formerly worked for this mineral 

 at .several points near Nuneaton and Hartshill. Fossils 

 occur in the shales, but they are indistinct and difficult 

 to find. The commonest shells are small species of 

 Liiigulella and OboldUt, and with these are trilobites of 

 the genus Agnostus. The collection of life-forms — such 

 as it is — appears to place the strata near the base of the 

 Tremadoc Slates — a division of the Upper Cambrian 

 formation finely developed in North Wales. If this 

 correlation be correct, the Hartshill quartzite probably 

 represents some portion of the Lingida flags, which in 

 "Wales lie below the Tremadoc slates, just as tlie Harts- 

 hill quartzite lies below the Stockingford shales. 



South of Nuneaton the quartzite is not seen, but the 

 overlying shales can be traced past Chilvers Coton 

 through Griflin Hollow to Marston Jabet. At the latter 

 village— in an old quarry near the Hall — the shales are 

 seen to dip tas/, at a low angle. They are here traversed 

 by an intrusive mass of diorite, which forms two large 

 bosses north-west of Marston Hall. The same easterly 

 dip is found at the other end of the strip of Cambrian 

 strata, north-west of Atherstone, where the beds — coal- 

 seams and all -r. .11 uvrr unA dip to tlir .Mst. 



Thus the ii-rtli-r;i-- 1-nlrr.J tlic W;irwi,-U-.liire coal- 

 field is formuil li\- ii \\:.yv..\\ fi'iiii,'.' i.f t":iiiiliri:iii and Pre- 

 Cambrian.str.,t;i.' ^^l,i.■l, nVr up'.shari.lv fnm, l..„euth the 

 Coal-Mea.sures (from «hich they are irii;.!-:,! . 1 l.y ii Hul- 

 of fauir), and occupy a tract of country ninr iU- tm milrs 

 long by from half-a-mile to a milJ ii. ^^illli. Tl.r 

 structure of the region is that of an aulicliunl, brukeii 

 through by a fault in the centre, between Nuneaton and 

 Atherstone, but preserving its crest to the south and to 

 the north of these towns. 



So far we have been concerned only with the eastern 

 side of the Warwickshire coal-firld. "it is now time to 

 turn our attention to the western Inninanrv, the distance 

 between the two being only fr.nu fnur U^ si.x miles. 

 <Fig. 2.) The line from Birmingham to Derby runs 

 parallel to the western outcrop of the coal-seams, and by 

 walking from Kingsbury to Fazeley (little stations, the 

 former five and the latter a mile or so, soixth of Tam- 

 worth), the jirincij)al facts can be seen in a few hours. 



Fig. 2.— Section across the Warwickshire Coal-field, from Harts- 

 hill to Dosthill. 1. Pre-C.-iinbrian Rocks ; 2. Cambrian Quartzite ; 

 3. Cambrian Shales ; 4. Coal-measures— the dotted line shows the 

 position of the limestone baud j 5. Red Marls of the Trias. 



From Kingsbury we walk northward for a mile along 

 the line, over the new red marls, which are separated by 



', fat] 



It from the Coal-measures. The latter are wel 

 exposed in a long cutting, in which five distinct seams of 

 coal can be recognised as black stripes between the beds 

 of blue shale and sandstone. The strata dip eastward at 

 a very high angle — 70° to 80° — so that in several of the 

 collieries the coal-seams have been followed from their 

 outcrop almost vertically downwards to a considerable 

 depth. The colliery - workings follow the coal-seams 

 eastward, but in a westerly direction the lowest seam is 

 broken and lost against the Cambrian strata, which here^ 

 as on the eastern boundary of the coal-field, have been 

 thrust up along a line of fault. After examining the 

 railway-cutting — which is entirely through the coal- 

 measures — we turn to the left (westward) to study 

 the Cambrian strata at Dosthill. Here there are 

 several exposures in field - pits, brick - works, Ac, 

 of grey and black shales, which are traversed 

 by countless numbers of worm - borings, so that 

 one Ls tempted to refer the strata to the " annelidean 

 stage " of the Cambrian epoch. The river Tame flows 

 from south to north through alluvial flats along the 

 western foot of the bold short ridge on which the village 

 of Dosthill stands. The hard, dioritic rock rises so 

 abruptly from the stream-course that at places the hill-side 

 is nearly vertical; other igneous rocks here are dykes of a. 

 greyish decomposed rock, similar to those near Nuneaton. 

 In a field-pit quite close to the high-road (on the west 

 side), three-quarters of a mile due south of Dosthill 

 Church, there is a very interesting section, showing a 

 " neck " of igneous rock rising through the shales, and 

 then spreading over them in all directions. In this 

 respect, it is almo.st unique in the Midland counties 

 (Fig. 3). 



ikiug through Cambrian shales at 



Standing on the summit of Dosthill the geological 

 structure of the region can be taken in at :i jl i r. The 

 rocks at our feet dip eastward, to rise ag.l 11-- 



hill ridge. The coal-field lies like a wiL ! '> 



faults, which meet at Spring Coppice, li\. ■ iK ~ i i.li- 

 east of Dosthill, but which diverge as they extend south- 

 ward. All the region between these two faults has 

 been uplifted from 1,000 to 6,000 ft. Formerly it ■< 



years ago were m such great demand, and which are abso- 

 lutely necessary to almost every industry in this country. 



